This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project involves the development of a new type of high-resolution functional imaging device. It combines 2-photon microscopy (TPM) and optical coherence tomography (OCT) into a single platform. These methods both utilize ultrashort-pulse near-infrared laser technologies and require beam scanning to form images. However, the information content in OCT is derived from scattered light, whereas TPM signals originate from non-linear electronic excitation of fluorescence. Together, they constitute the intravital microscope equivalent of a phase contrast and fluorescence overlay image in a single cell. But with TPM/OCT, tomographic images can be formed at depths of 0.5-1 mm in tissue. Recently, a French group demonstrated, for the first time, that it is possible to design a system that combines the 2 approaches. We propose to take this work several steps further by incorporating key optical design elements that will optimize our sensitivity to cancer relevant pro cess es. Our intravital functional imager will be capable of simultaneously imaging neovascular structure, blood flow direction/velocity, extracellular matrix structure (collagen/elastin fibers), and cellular redox state (e.g. oxidative stress). These images will be formed from intrinsic signals, i.e. interferograms and 2-photon excited autofluorescence, without the addition of exogenous dyes/probes. However the system can also be used with added chromophores such as fluorescent dyes and gene expression probes (GFP, etc). Images will be rendered in real time; so live animal model studies can be conducted in model tumor systems simply by placing the subject on an imaging stage. In addition, the instrument will be constructed so that studies of human skin lesions can be performed in vivo, with the goal of developing a technique that provides information comparable to histopathology.